The preferred embodiments of the present invention generally relate to improvements in a medical X-Ray imaging system. More particularly, the present invention relates to a system and method for synchronizing the acquisition of images with the cardiac phase for dual energy imaging.
The usage of X-ray systems in clinical imaging and diagnosis enjoys widespread acceptance. Several types of X-ray imaging methodologies may be employed to image different anatomical areas or to provide differing diagnostic tools. One such X-ray imaging methodology is Dual Energy (DE) imaging.
Dual Energy (DE) is a clinical application wherein two x-ray images are acquired at different X-ray energies. The two X-ray images are then combined to provide tissue-subtracted images, e.g., soft tissue and bone images. One clinical application of DE is diagnosis of lung cancer with X-ray. In practice, the soft tissue image improves sensitivity by removing the structured noise due to the bones, and the bone image improves specificity by showing if a nodule is calcified and hence benign.
With flat panel X-ray detector technology, the two X-ray images are typically successively acquired with two separate X-ray exposures at different energies. In order to minimize patient motion artifacts between the two X-ray images, the time between the X-ray images is typically minimized (typically on the order of 200 ms). In order to minimize diaphragm motion, the patient is typically asked to hold their breath. However, involuntary patient motion such as the contraction of the heart, cannot be avoided. Significant motion of the heart between the two X-ray images may yield poor image quality due to imperfect tissue cancellation in the subtracted images. The poor image quality may lead to possible missed cancer nodules in the lung regions surrounding the heart.
Thus, a need has long been felt for a system that provides for better diagnostic X-ray imaging. Specifically, a need has long been felt for an improved diagnostic X-ray imaging system for employing DE. Further, a need has long been felt for such an improved DE system that minimizes the effect of involuntary patient motion in the resultant X-ray images in order to improve image quality and consequent diagnosis.
The present invention provides a system and method for improving the image quality of an X-ray image of a patient in a dual energy X-ray imaging system. The X-ray emitter emits high and low energy X-rays which may be combined with offsets. Both the high and low energy X-rays are triggered by a heart cycle monitor which determines the patient""s cardiac events. An X-ray detector receives the X-ray emissions and offsets and forms X-ray images. The heart monitor is employed to synchronize the X-ray imaging of the patient with the patient""s cardiac cycle in order to minimize the effect of involuntary patient motion and improve the resultant X-ray images.